不同程度急性等容量血液稀释对兔小肠粘膜的影响

目的 探讨常温下不同程度急性等容量血液稀释(ANH)对家兔小肠粘膜的影响.方法 选择健康成年家兔32只,体重2.0～2.5 kg,随机分为4组(n=8),对照组(C组)不行血液稀释;其余3组血液稀释的目标Hct分别为24%(H1组)、18%(H2组)和12%(H3组).经股动脉放血:H1组、H2组、H3 组所需放血量=2×体重×每公斤体重所含体液量×(初始Hct-目标Hct)/(初始Hct+目标Hct),股静脉经30 min输入等容量6%羟乙基淀粉200/0.5行ANH.于ANH前(T0)及ANH后8 h(T1)时采集肠系膜上静脉血样0.5 ml,采用酶联免疫吸附法测定血浆TNF-α浓度.于T1时取小肠粘膜组织,观察病理学结果.结果 与T0时比较,T1时H2组、H3组肠系膜上静脉血浆TNF-α浓度升高(P＜0.01),H1组差异无统计学意义(P＞0.05).与C组比较,H2组和H3组肠系膜上静脉血浆TNF-α浓度升高(P＜0.01),H1组差异无统计学意义(P＞0.05).H1组小肠粘膜未见明显损伤,H2组轻度损伤,H3组损伤严重.结论 6%羟乙基淀粉200/0.5行ANH,当Hct为24%时,对家兔小肠粘膜无明显影响;当Hct≤18%时,可诱发小肠粘膜损伤.

Effect of different degrees of acute normovolemic hemodilution on mucous membrane of small intestine in rabbits

Objective To investigate the effect of different degrees of acute normovolemic hemodilution (ANH) with 6% HES 200/0.5 on mucous membrane of small intestine in rabbits. Methods Thirty-two adult rabbits weighing 2.0-2.5 kg were randomly divided into 4 groups ( n = 8 each): Ⅰ control group underwent no ANH, and Ⅱ, Ⅲ, Ⅳ group underwent ANH with hematocrit (Hct) reduced to 24%, 18% and 12% respectively (group H1-3 ). The animals were anesthetized with 20% urethane 4 ml/kg, thracheostomized and mechanically ventilated (VT = 8 ml/kg, RR = 50 bpm). The body temperature was maintained at 36.5-37.6 ℃. Left carotid artery was cannulated for MAP monitoring and blood sampling. Right jugular vein was cannulated for CVP monitoring. Blood withdrawn from femoral artery was simultaneously replaced by iv infusion of equal volume of HES (200/0.5) until the target Hct was achieved. Blood samples were obtained from superior mesenteric vein (SMV)for determination of plasma concentrations of TNF-α before ANH(T0) and at 8 h after ANH (T1). Small intestinal mucosal tissues were obtained at T1 to observe the pathological changes by electron microscopy. Results Compared with those at T0, plasma concentrations of TNF-a in SMV were significantly increased at T1 in group H2 and H3 ( P ＜ 0.01 ), but no significant change was found in group H1 ( P ＞ 0.05). Compared with group C, plasma concentrations of TNF-α in SMV were significantly increased in group H2 and H3 ( P ＜ 0.01 ), but no significant change was found in group H1 ( P ＞ 0.05). No injury was found in mucous membrane of small intestine in group H1 . The injury to mucous membrane of small intestine was mild in group H2 and severe in group H3 . Conclusion ANH with 6% HES 200/0.5 does not affect mucous membrane of small intestine when Hct is reduced to 24% The injury to mucous membrane of small intestine occurs when Hct is reduced to≤ 18%.